Methods

A systematic search identified relevant published reports regarding ischaemic stroke risk as associated with migraine. Prespecified criteria: (1) included studies with case-control or cohort study designs with reported or extractable adjusted quantitative estimates of the risk of ischaemic stroke in migraineurs compared with non-migraineurs and (2) excluded studies of transient stroke-like syndromes, migrainous infarction, silent infarction and those that reported outcomes as associated with mixed stroke types (eg, haemorrhagic and ischaemic stroke). Of note, all but two studies from the most recent prior meta-analysis1 and nine additional studies were included in the present study. Included studies were required to implement standard definitions, or reasonable variations thereof, for both stroke and migraine.

OR, RR, HR and incidence rate ratios were used to estimate effect sizes. Evaluations of clinical, methodological and statistical heterogeneity of the included studies were assessed using the Cochrane Collaboration Guidelines …